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.\"     @(#)ctags.1	8.1 (Berkeley) 6/6/93
.\"
.Dd June 6, 1993
.Dt CTAGS 1
.Os BSD 4
.Sh NAME
.Nm ctags
.Nd create a tags file
.Sh SYNOPSIS
.Nm
.Op Fl BFadtuwvx
.Op Fl f Ar tags_file
.Ar name ...
.Sh DESCRIPTION
.Nm
makes a tags file for
.Xr ex 1
from the specified C,
Pascal, Fortran,
.Tn YACC ,
lex, and lisp sources.
A tags file gives the locations of specified objects in a group of files.
Each line of the tags file contains the object name, the file in which it
is defined, and a search pattern for the object definition, separated by
white-space.
.Pp
Using the
.Ar tags
file,
.Xr ex 1
can quickly locate these object definitions.
Depending upon the options provided to
.Nm ,
objects will consist of subroutines, typedefs, defines, structs,
enums, and unions.
.Bl -tag -width Ds
.It Fl a
append to
.Ar tags
file.
.It Fl B
use backward searching patterns
.Pq Li ?...? .
.It Fl d
create tags for
.Li #defines
that don't take arguments;
.Li #defines
that take arguments are tagged automatically.
.It Fl F
use forward searching patterns
.Pq Li /.../
(the default).
.It Fl f
Places the tag descriptions in a file called
.Ar tags_file .
The default behavior is to place them in a file called
.Ar tags .
.It Fl t
create tags for typedefs, structs, unions, and enums.
.It Fl u
update the specified files in the
.Ar tags
file, that is, all
references to them are deleted, and the new values are appended to the
file.  (Beware: this option is implemented in a way which is rather
slow; it is usually faster to simply rebuild the
.Ar tags
file.)
.It Fl v
An index of the form expected by
.Xr vgrind 1
is produced on the standard output.  This listing
contains the object name, file name, and page number (assuming 64-line pages).
Because the output will be sorted into lexicographic order,
it may be desirable to run the output through
.Xr sort 1 .
Sample use:
.Bd -literal -offset indent
ctags \-v files \&| sort \-f > index
vgrind \-x index
.Ed
.It Fl w
suppress warning diagnostics.
.It Fl x
.Nm
produces a list of object
names, the line number and file name on which each is defined, as well
as the text of that line and prints this on the standard output.  This
is a simple function index which can be printed out for reading off-line.
.El
.Pp
Files whose names end in
.Sq \&.c
or
.Sq \&.h
are assumed to be C
source files and are searched for C style routine and macro definitions.
Files whose names end in
.Sq \&.y
are assumed to be
.Tn YACC
source files.
Files whose names end in
.Sq \&.l
are assumed to be lisp files if their
first non-blank character is `;', `(', or `[',
otherwise, they are treated
as lex files.  Other files are first examined to see if they
contain any Pascal or Fortran routine definitions; if not, they are
searched for C-style definitions.
.Pp
The tag
.Li main
is treated specially in C programs.  The tag formed
is created by prepending
.Ar M
to the name of the file, with the
trailing
.Sq \&.c
and any leading pathname components removed.  This
makes use of
.Nm
practical in directories with more than one
program.
.Pp
Yacc and lex files each have a special tag.
.Ar Yyparse
is the start
of the second section of the yacc file, and
.Ar yylex
is the start of
the second section of the lex file.
.Sh FILES
.Bl -tag -width tagsxxx -compact
.It Pa tags
default output tags file
.El
.Sh DIAGNOSTICS
.Nm
exits with a value of 1 if an error occurred, 0 otherwise.
Duplicate objects are not considered to be errors.
.Sh SEE ALSO
.Xr cc 1 ,
.Xr ex 1 ,
.Xr lex 1 ,
.Xr sort 1 ,
.Xr vgrind 1 ,
.Xr vi 1 ,
.Xr yacc 1
.Sh BUGS
Recognition of
.Em functions  ,
.Em subroutines ,
and
.Em procedures
for
.Tn FORTRAN
and Pascal is done in a very simple-minded way.  No attempt
is made to deal with block structure; if you have Pascal procedures
with the same name in different blocks, you lose.
.Nm
doesn't
understand about Pascal types.
.Pp
The method of deciding whether to look for C, Pascal, or
.Tn FORTRAN
functions is a hack.
.Pp
.Nm
relies on the input being well formed, so any syntactical
errors will completely confuse it.  It also finds some legal syntax
to be confusing; for example, because it doesn't understand
.Li #ifdef Ns 's
(incidentally, that's a feature, not a bug), any code with unbalanced
braces inside
.Li #ifdef Ns 's
will cause it to become somewhat disoriented.
In a similar fashion, multiple line changes within a definition will
cause it to enter the last line of the object, rather than the first, as
the searching pattern.  The last line of multiple line
.Li typedef Ns 's
will similarly be noted.
.Sh HISTORY
The
.Nm
command appeared in 
.Bx 3.0 .
